Effect of Retinal Photocoagulation on Intraretinal Lipid Exudates in Diabetic Macular Edema Documented by Optical Coherence Tomography

Purpose: To study the changes in the distribution and morphologic features of intraretinal microexudates after macular photocoagulation.

Design: Prospective cohort study.

Participants: Thirteen treatment-naïve patients with clinically significant macular edema in type 2 diabetes.

Methods: Patients were treated with focal macular photocoagulation. Changes in the localization of hyperreflective foci were analyzed by spectral domain (SD) optical coherence tomography (OCT) during follow-up at day 1, week 1, and months 1, 2, 3, and 4 in defined areas. Further, fundus photography and infrared imaging were performed at all visits and findings were correlated to OCT results.

Main Outcome Measures: Changes in retinal morphologic features detected in OCT.

Results: A dynamic change in the distribution pattern of hyperreflective foci was observed over 4 months after the photocoagulation. With the decrease of retinal thickness, the dots either resolved completely or became confluent at the apical border of the outer nuclear layer, and finally formed ophthalmoscopically detectable hard exudates during extended follow-up. In the event of retinal thickening despite laser treatment, the hyperreflective dots maintained their previous distribution throughout all retinal layers. As a fourth response, dissemination of plaques of hard exudates into multiple, separate, hyperreflective foci were detected.

Conclusions: Hyperreflective foci in the retina seem to represent precursors or components of hard exudates. Their specific localization depends greatly on the presence of microvascular extravasation and intraretinal fluid accumulation. Retinal photocoagulation has a major impact on retinal edema and subsequently on the distribution of intraretinal lipid deposits.

Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.